Solitary congenital fibromatosis (infantile myofibromatosis) of bone.

Congenital fibromatosis is a rare and benign myofibroblastic tumor that may occur in either a solitary or multicentric form. The soft-tissue form of this entity is well recognized. This report analyzes the clinical and pathologic features of 14 cases of congenital fibromatosis in which the tumor existed as a solitary lesion in bone. Most of the tumors (71%) were in patients who were 2 years old or younger. All but one tumor involved the craniofacial bones. Radiographically, they were purely lucent lesions in which a sclerotic rim was visible in each skull lesion. The myofibroblastic appearance closely resembled the microscopic features seen in the soft-tissue counterpart. For appropriate surgical management, it is imperative to recognize that this tumor occurs as a solitary lesion in bone and that it is distinct from other, more aggressive fibrous lesions.